Difficult to make any recommendations without seeing a schematic to find Exactly How and whats there already!
Is it a circlotron? 6n45c is basically an EL509, so this amp aint THAT huge!
Is this an OTL? or does it have output Tx? Why did/how did you add an Interstage Tx? (A step backwards IMHO, Unless you paid a fortune for the interstage, as GOOD ones are megabux!)
What do you mean by 'Slow'?? Lack of treble? Boomy bass? lack of clarity?--what?
How does a Slow amp sound in comparison to a 'Fast' amp!!
--Like asking how can I improve a cake recipe--Without the recipe to start with!
Blindly chopping/changing components is not the way forward,--no matter WHAT the 'audiofools' say!
quote: Is it a circlotron? 6n45c is basically an EL509, so this amp aint THAT huge!
here you go sir..
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The amp is a circlotron..what i mean by slow is transit response seems slow its hard to describe...that's why i was playing around with interstage (eletraprint) transformers etc.......
I do remember that the man said it was kinda build/designed off of the electrovoice 100a etc..
Please help i would like to get these back up and running..
Thanks for the link but i seen that and i dont necessarily want to put it back that way..
well, you mentioned electrovoice
but your isn't, since it appears to be pure OTL
but if the builder said electrovoice style, I guess it means circlotron design
I don't how much power you can do with such 4 tubes
maybe on the low side
could it be the reason you feel its a bit 'slow' ?
lack of power ?
or high output impedance maybe ?
could be your speakers have a problem with this ?
maybe you need new tubes ?
and proper adjustment ?
but your isn't, since it appears to be pure OTL
but if the builder said electrovoice style, I guess it means circlotron design
I don't how much power you can do with such 4 tubes
maybe on the low side
could it be the reason you feel its a bit 'slow' ?
lack of power ?
or high output impedance maybe ?
could be your speakers have a problem with this ?
maybe you need new tubes ?
and proper adjustment ?
ahh, ok, I thought about that too, but....
well, then the output trafo appears to be a 'converted' mains power trafo
but 300watt
and its not 'just' power consumption you measure ?ahh, ok, I thought about that too, but....
well, then the output trafo appears to be a 'converted' mains power trafo
but 300watt
No sir 300wpc...the power transformer is sized correctly and to look like the output (symmetry) he winds his own power and outputs!!!
I actually saw him bench it...300wpc! thats why i wanted this monster...super hi quality build....the guy who built this is my friends buddy in WI his name is Joe halser .....but he suggests to just put it back to original etc..but i want to move on to a different/more better topology
I would suggest doing a frequency response test, a distortion spectrum test at low and at moderate power out, and an output impedance test first, before doing any mods. Also determine whether global feedback is used. A schematic would be most usefull too. Then any deficiencies can be dealt with in designing a new front end if required, or just some mods to the existing setup. The 4 6n45c tubes should be capable of 300 Watts. It shouldn't sound "slow" unless something is remiss.
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Sir I cannot do any testing until these amps are functional.....hence the reason for posting......anyone have a better working idea for voltage gain and drive?..both have to use 9 pin tubes...so no octal or loctal..etc.
Thanks
Lawrence
Sir I cannot do any testing until these amps are functional.....hence the reason for posting......anyone have a better working idea for voltage gain and drive?..both have to use 9 pin tubes...so no octal or loctal..etc.
Thanks
Lawrence
re: Sk8Ter
You mentioned a "12BL7 driver bootstrapped", did you mean 12BH7 or 12BY7?
The 12BH7 might be a bit anemic for driving paralleled 6n45c tubes, possibly leading to "slow" sounding. 12BY7 should work well, but would require two of them.
Suggest drawing up a schematic of the unit, not that hard. What B+ voltages are available? Screen supply? Negative volts available for a CCS? Fixed output tube bias's with pots? Filament voltages available? Mosfet followers to the output tube grids?
You mentioned a "12BL7 driver bootstrapped", did you mean 12BH7 or 12BY7?
The 12BH7 might be a bit anemic for driving paralleled 6n45c tubes, possibly leading to "slow" sounding. 12BY7 should work well, but would require two of them.
Suggest drawing up a schematic of the unit, not that hard. What B+ voltages are available? Screen supply? Negative volts available for a CCS? Fixed output tube bias's with pots? Filament voltages available? Mosfet followers to the output tube grids?
Yes.... my bad I did mean 12bh7..sorry about that...this is not my forte....let me look into and possibly draw a schematic ...
So--Just to clarify,
You messed about with them, Now they dont work....?
--And, you're expecting us to 'fix' them whilst not knowing exactly WHAT you have done, and work in a dark-room, with no schematic..??!!
Yup--We gotta be psychic to help ya!
So--Just to clarify,
You messed about with them, Now they dont work....?
--And, you're expecting us to 'fix' them whilst not knowing exactly WHAT you have done, and work in a dark-room, with no schematic..??!!
Yup--We gotta be psychic to help ya!
I did/don't expect YOU or anyone else to fix them I can do that and put them back to original like the electrovoice 100a....SO what i asked for all intense and purposes is to help with a newer better topology....that will work better then the 12ax7/12bh7..
Lawrence
"search the tube forum there's tons of info on input/ driver/phase splitter "
The usual driver/splitters aren't likely to work well here due to the Circlotron configuration requiring huge grid drive signals (50% CFB). We're in "Mac driver territory" here and we don't have a clue about the bandwidth of the OTs (or even their Zpri) or the amount of global feedback that was used before. Does anyone even have any data/curves for the output tubes? Maybe just use EL519 specs or similar.
(I'm also suspicious of the linearity of anything like the EL509/6KG6, maybe a change to another Sweep tube is all that's needed here.)
It should be possible to configure a bootstrapped driver stage, since it apparently had that before. But global loop gain/stability issues are unknown. For some real driver "grunt", something like a video pentode/triode 9 pin combo tube (9DX base) could keep to the original double 9 pin socket budget. High gm 5 Watt driver pentodes are readily available in this format, but could be difficult to tame their likely HF parasitics as well as the global stability issue. (the pentode would require some local Schade'ing to control loop gain and maintain the CFB output effect via plate Rp) Other, tamer, 9 pin candidates would be some of the vertical amp dissimilar dual triodes. Easier to configure if we know how much gain is acceptable.
One could approach this as a general Circlotron/Mac front end project for Sweep tubes. Except ---- Big big problem --- without test equipment available to the OP. An O'scope with HV probes, signal gen. and DVM are really mandatory here. Spice models for any of the likely tubes are almost certainly non-existant, besides the OT info, so Simulation modeling is out.
The usual driver/splitters aren't likely to work well here due to the Circlotron configuration requiring huge grid drive signals (50% CFB). We're in "Mac driver territory" here and we don't have a clue about the bandwidth of the OTs (or even their Zpri) or the amount of global feedback that was used before. Does anyone even have any data/curves for the output tubes? Maybe just use EL519 specs or similar.
(I'm also suspicious of the linearity of anything like the EL509/6KG6, maybe a change to another Sweep tube is all that's needed here.)
It should be possible to configure a bootstrapped driver stage, since it apparently had that before. But global loop gain/stability issues are unknown. For some real driver "grunt", something like a video pentode/triode 9 pin combo tube (9DX base) could keep to the original double 9 pin socket budget. High gm 5 Watt driver pentodes are readily available in this format, but could be difficult to tame their likely HF parasitics as well as the global stability issue. (the pentode would require some local Schade'ing to control loop gain and maintain the CFB output effect via plate Rp) Other, tamer, 9 pin candidates would be some of the vertical amp dissimilar dual triodes. Easier to configure if we know how much gain is acceptable.
One could approach this as a general Circlotron/Mac front end project for Sweep tubes. Except ---- Big big problem --- without test equipment available to the OP. An O'scope with HV probes, signal gen. and DVM are really mandatory here. Spice models for any of the likely tubes are almost certainly non-existant, besides the OT info, so Simulation modeling is out.
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